In which of the following cases will Federal law prohibit a state from imposing an income tax on net income?

a. The business has a retail outlet store in the state.

b. The business has its corporate headquarters in the state and generates sales from there.

c. Orders are taken within the state and accepted at corporate headquarters outside of the state and shipped from a location outside of the state.

d. Orders are taken within the state and accepted at corporate headquarters outside of the state and shipped from a location inside the state.